1. Field of the Invention
This present invention relates to a method for forming an opto-electronic device, and more particularly to a method for forming an opto-electronic device through a solid state growth process at low temperature.
2. Description of the Prior Art
In recent years, the opto-electronic devices, e.g. Light-Emitting Diodes (LED), solar cells and light sensors, have become more and more popular. During forming an LED, the electrodes of the LED are formed on a substrate consisted of compound semiconductor, e.g. GaAs, GaN or InP. For forming well ohmic contact between the electrodes and the substrate, the LED has to be treated at the temperature being higher than 400 degrees centigrade, i.e. 400° C. If an improper material with a melting point being lower than 400 degrees centigrade is used to be on of the elements of the LED device, the improper material may be melted or be transformed lattices of itself in a high temperature process being higher than 400° C., e.g. Rapid Thermal Annealing Process, RTP. The material of the compound semiconductor and the active layer may be destroyed to reduce the quality and the illuminant efficiency of the opto-electronic device, i.e. the LED. The yield for producing the opto-electronic devices is also reduced because the structure of the elements is destroyed.
Futhermore, the illuminant efficiency of an LED device with an opaque substrate has to be increased. An opto-electronic device, e.g. an LED device, with a transparent substrate is constructed to improve the disadvantage of an opto-electronic device with an opaque substrate that absorbs light and decreases the illuminating efficiency of the opto-electronic device. However, for forming ohmic contact between electrodes and the substrate, almost all elements of the opto-electronic device have to suffer the temperature being higher than 400 degrees centigrade. The heat produced in the process at the temperature being higher than 400 degrees centigrade limits the material of elements. The materials of elements of the opto-electronic device must be selected from the materials with the melting point or the glass transition temperature that is higher than 400 degrees centigrade.
Hence, it is an important objective for developing a method for forming an opto-electronic device, e.g. an LED device, to reduce the disadvantage of the prior art, increase the selectivity of the materials of the elements and increase the yield for producing the opto-electronic device.